Thanks for the clarification. Yes, you're right. But it's very difficult to obtain any quantitative picture from the article you provided. It's peppered with adjectivation, and adverbialisation directly derived from adjectives in almost every paragraph:
cruel, brutally efficient
cautiously, suspiciously
ruthlessly, unhesitatingly, comprehensively, systematically, meticulously
nearly certain, enough partial proofs, strong circumstantial case...,
I'm aware that Hassner scarcely has any other way to qualify these procedures, their limits, compulsory character, range of applicability, etc., as the truth is we are inevitably constrained to use only historical analysis to infer these qualifications. A lot is presumably lost in "historical noise." Maybe contemporary sources were more interested in justifying their methods than really conducting a serious experimental analysis. I really don't know. I prefer to position myself among the sceptics and the cautious of the premise that torture is actually efficient in regards to obtaining information.
Let me, please, insist on the particular point from the article that gave me pause:
IOW: Most of the victims did not provide that information, if I understood correctly.